Scavenging two stroke cycle internal combustion engine



Jan. 5, 1932. K. MOHR ET AL SCAVENGING TWO-STROKE CYCLE INTERNAL COMBUSTION ENGINE Filed May 17, 1930 Patented Jan. 1932- mm STATES PATENT. orrlcn i =1. Mona, or KIEL, m WOLFGANG nnvnmann, or xmn-mts'mrcnsnonr, GER- OF KIEL-G-AARDEN, GERMANY MANY, ASSIGNORS '10 FRIED. KBUPP GERMANIAWERFT .AKTIENGESELLSGHAFT,

SCAVENGING TWO STROKE CYCLE INTERNAL COMBUSTION ENGINE Application filed M11717, 1930, Seflat1io. 453,319, and in Germany February 24,1980.

The invention has for its object a port arrangement for two-stroke cycle internal combustion engines having scavenging inlet ports directed toward the cylinder cover and cf- 5 fecting transverse scavenging of the cylinder. In engines of this ty e, more particularly those of the lon stro e type, it is very diflicult, even when t e scavening ports are directed very steeply toward the cylinder cover, to obtain satisfactory scaven ing of the cylinder, because of the fact t atthe.

current whirl above the piston end face as a consequence of the inlet ports being directed toward the cylinder cover, which whirl tends to flow off toward the outlet ports and thus draws the scavenging current downward, whereby a premature .reversal of the current toward the outlet orts is caused. These two whirls of remain ng waste gases therefore seriously derogate the effective guidance of the scavenging current and by interminglin with the fresh scavenging air substantially reduce both quality and quantity of the really operative air of combustion. v

' The invention has for its object to obviate these drawbacks and consists in the fact that additional inlet and outlet scavenging ports are provided on the cylinder in'the follow- .ing manner. Two additional inletports are arranged oppositely to one another'and about at right angles to the direction of the scavenging current, through which inlet iliary air currents enter the c hnder and while fiowin'gover the piston en face in the direction between the cylinder axis and the outlet ports drive the lower whirl into the scavenging current so thatit flows to the outlet ports together with the latter. The

rts auxfurther provided additional outlet ports are arranged above the main inlet ports and carry away whirls formed above the main inlet ports. so that the entering air current is sucked toward the cylinder wall.

In order that the invention can be more readily understood, an embodiment of the same is illustrated b way of example in the drawings in which Figure 1 is a vertical section through a cylinder of an internal combustion engine fitted with known ports for transverse scavenging and shows the course of the scaven'ging current in the cylinder,

Figure 2 is a horizontal section through this cylinder,

Figure 3 is va section similar to that shown in Figure 1 and illustrates the course ofthe transverse scavenging current when providing two auxiliary scavenging current inlet ports and additional outlet ports in accordance with the invention.

Fig. 4 is a horizontal section through the 'cylinder shown in Fig. 3.

Referring first to Figures 1 and 2, a denotes the main inlet ports and b the main outlet.

ports, while 0 denotes the piston reciprocating in the working cylinder of a two-stroke internal combusion engine. The scavenging air flows through the cylinder in the direction of the full line arrows, the waste gas whirls d V and e formed being indicated by dotted line arrows.

As to be seen from Fi re l,the scavenging current owin to the "recting efiect of the inlet ports alias the tendency to rise to the cylindefcover, but is deflected from the cylinder wall by the edge whirls f formed between it and the cylinderwall, and is deflected furthermore prematurely toward the outlet ports 7) by the whirl (1 formed above the piston end face. Thus the cylinder cover is not 1 the whirl d for sake of clearness is illus trated perspectively.

Figures 3 and 4 lllu strate in what *manner this .drawback is eliminated 'accordingto the invention. As to be seen, additional outlet touched by the scavengingair current so that the whirl e is formed above the latter. In

Figure 2 which is a cross section of Figure ports 9 are provided above the inlet rtsa while further two positely locate inlet hare provid above thepiston end ace. These" latter ports h have directions such as to cause the additional scavening air enterin through them to stream over the concave piston end face between the cylinder axis and the main outlet ports. The course of these auxiliary currents is indicated by ar- 10 rows in Figures 3 and 4. These two auxiliary air currents are reversed by the concave piston end face in such a manner as to meet from the side the circumference of the whirl d illustrated in Figure 1 and are led toward the 5 center of the piston c by the'rotation of the whirl d. Thereby whirl 11 itself is urged into the rising scavenging air current and replaced from below by the fresh air entering through the additional ports h. Any emigra- 90 tion of whirl (1 toward the main outlet ports cannot take lace as the two additional air currents are tween the whirl and the outlet ports. Inthismannerthedangeriseliminated of the greater portion of the main scavenging '25 air current fed to the cylinder being so to speak short-circuited toward the main outlet ports and of a waste gas whirl 6 being formed near the cylinder cover due to premature reversal of the current in' consequence of such short-circuiting. Through the additional outlet ports g the edge whirls flare sucked away to the atmosphere and, consequently, .the scaven current flows upward close along the will: er wall till the cylinder 5' cover. Any formation of a top whirl e is thus not longer possible.

The deflection aimed at toward the cylinder wall of the scavenging air current is already achievedby means of additional outlet ports 40 of small height so that a notable loss of scavenging air does 'nottake place. The ports g either extend but little or not at all beyond the main outlet ports 6 and increase the time cross section for the exhaust. What we claim and desire to secure by Letters Patent, is I A cylinder for two-stroke cycle internal combustion engines having scavenging inlet ports directed toward'the cylinder cover and oppositely situated outlet ports, additional inlet ports located about at right angles relatively to the direction of the transverse scavenging current passing through said inlet and outlet ports and generally directed towards a point between the cylinder axis and said outlet rts, and additional outlet ports situated a ve said first-mentioned inlet v. The foregoing specification si ed at Hamburg German this 2nd da of a 19308 KAhZLMOHR y WOLFGANG 

